单层PtSe₂中空位驱动的电子重构：形成热力学与电荷态
Vacancy-Driven Electronic Reconstruction in Monolayer PtSe$_2$: Formation Thermodynamics and Charge States
中文总结 AI 辅助
本研究基于第一性原理计算，探究单层PtSe₂中各类空位的形成热力学、电荷态等，发现Vₛₑ形成能最低，空位扩散受抑制，缺陷可调控其光学性质，为其器件设计提供指导。
中文摘要 AI 辅助
层状过渡金属二硫化物是二维材料的重要平台，其不可避免的本征缺陷为调控物理性质提供了新的自由度。本研究基于第一性原理计算，系统探究了单层PtSe₂中Pt空位（Vₚₜ）、Se空位（Vₛₑ）及复合空位的形成能、电荷态与电子结构特征。结果表明，空位形成能对化学势高度敏感，但Vₛₑ结构始终表现出最低的形成能；电荷缺陷计算揭示了Vₛₑ和Vₚₜ稳定电荷态区间随费米能级的变化关系，描述了本征空位在不同电子化学势下的电荷态演化。爬升图像 nudged 弹性带计算显示，Vₛₑ和Vₚₜ的迁移势垒较高，表明室温下空位扩散受到强烈抑制；短时间从头算分子动力学模拟证实，在模拟时间窗口内未发生即时结构坍塌。光学性质计算表明，点缺陷显著改变了单层PtSe₂的介电响应，并产生与带隙内缺陷态相关的新低能吸收通道。这些发现为单层PtSe₂中缺陷介导的电子与光学性质调控提供了新见解，为其潜在器件设计提供了指导。
英文摘要
Layered transition metal dichalcogenides are an important platform for two-dimensional materials, where the inevitable intrinsic defects provide new degrees of freedom for tuning their physical properties. Based on first-principles calculations, this work systematically investigates the formation energies, charge states, and electronic structural characteristics of V$_{\mathrm{Pt}}$, V$_{\mathrm{Se}}$, and composite vacancies in monolayer PtSe$_2$. The results indicate that while vacancy formation energies are highly sensitive to chemical potentials, the V$_{\mathrm{Se}}$ structure consistently exhibits the lowest formation energy. The charge defect calculation reveals the stable charge state intervals of V$_{\mathrm{Se}}$ and V$_{\mathrm{Pt}}$ as a function of the Fermi level, thus describing the evolution of the charge states of intrinsic vacancies at different electronic chemical potentials. Climbing Image Nudged Elastic Band calculations reveal high migration barriers for V$_{\mathrm{Se}}$ and V$_{\mathrm{Pt}}$, indicating strongly hindered vacancy diffusion at room temperature, while short Ab Initio Molecular Dynamics simulations confirm the absence of immediate structural collapse within the simulated time window. Optical property calculations indicate that point defects significantly alter the dielectric response of monolayer PtSe$_2$ and generate new low-energy absorption channels associated with in-gap defect states. These findings provide new insights into defect-mediated electronic and optical property modulation in monolayer PtSe$_2$, offering guidance for its potential device design.
